Lemna minor is a member of the Lemnaceae family and is recognized to be a tiny infrequently flowering plant that often grows while floating in still (e.g., ponds) or slowly-moving fresh water. The species occurs throughout the world except in the coldest regions. Such plant commonly is known simply as Duckweed. Plant coloration between green and greenish-brown commonly is observed, while the plant floats as a blanket on the water surface. See the PLANTS Profile for common Lemna minor provided by the United States Department of Agriculture, Natural Resources Conservation Service. There the typical and entangled roots of Lemna minor are illustrated. In recent years, interest has focused on the use of plants for possible renewable energy source, as well as for industrial utilization. Lemna minor plants have been included in this interest.
Such Lemna minor plants are generally adapted to produce carbohydrates through the mixotropic conversion of carbon dioxide while deriving nourishment via both autotropic and heterotropic mechanisms. For instance, organic matter (even contamination and waste) present in water and carbon dioxide from the air can be combined by the tiny plants. Carbohydrates in the water are broken down into simple sugars. During growth phosphorus and nitrogen are consumed. Unwanted substances are removed from the water. Upon harvest, the resulting plants can be burned directly to yield a source of fuel or energy. Alternatively, the plants can be processed to form a biofuel wherein the plants serve as a feedstock for ethanol or methane production. Less reliance upon fossil fuels is required upon the utilization of such energy source. The plant further serves as a natural water purifier.
It is recognized that a profuse root formation provides floating Duckweed plants with the ability to well receive nutrients present in water during biosynthesis. However, common Lemna minor plants are recognized to possess such an extensive production of long and entangled roots that efficient planting and harvest is complicated. This plant morphology has been found to interfere with commercially viable large scale biomass production. The plants also commonly also require culture while utilizing relatively high light conditions.
When common Dwarf Duckweed (i.e., Wolffia arrhiza) is considered for biomass production, it is found that such plants can be readily separated from one another since the plants are completely rootless. However, such absence of roots manifests a decreased ability to absorb nutrients from water even in the presence of high light conditions. Accordingly, photosynthesis proceeds at a diminished rate in such species when compared to that of common Lemna minor. 